Carburetors for high performance internal combustion engines used for racing vehicles usually are of high capacity and are relatively expensive. The carburetors as well as many other parts and components of a racing vehicle are subject to being changed so as to modify the performance of the vehicle. In some instances, a carburetor must be changed in response to the change of or modification to an engine of the vehicle. In other instances, the capacity of the carburetor must be modified, as by changing out the carburetor, to achieve maximum engine performance. Most carburetors are produced by casting which usually does not create a precision shape and it becomes cost prohibitive to machine the critical surfaces of a cast venturi in order to modify the performance characteristics of the venturi. Therefore, it would be desirable to be able to expediently modify the shape and other features of venturi surfaces of a carburetor by replacing one venturi surface with another venturi surface.